DENVER, Aug. 29 -- The media's watchdogs, having spent weeks barking up the wrong trees in search of John McCain's running mate, immediately started growling at his surprise choice.

In the moments after cable news reporters confirmed Friday that McCain had chosen Sarah Palin, the journalistic talk turned not to the groundbreaking choice of a woman but to whether Alaska's rookie governor is prepared to be a heartbeat from the presidency.

"There will be a lot of questions about whether someone who was mayor of Wasilla, Alaska, just three years ago, whether she's ready to be commander in chief," NBC political director Chuck Todd told viewers.

"She's been in office only two years -- is she qualified to be commander in chief?" asked CNN's John King. "It makes you wonder: Where's the beef?" said MSNBC's Kevin Corke. "For so many Americans, Governor Palin is a bit of a mystery," said Fox's Bill Hemmer.

In marked contrast to last week's coverage of Joe Biden, a Senate committee chairman who had relationships with the media for three decades before becoming Barack Obama's running mate, the reporters and pundits who constantly speculated that Mitt Romney or Tim Pawlenty might join the Republican ticket were caught flat-footed.

"We don't know that much about her," CNN's Dana Bash acknowledged.

Frank Sesno, a professor of media and public affairs at George Washington University, said journalists are in for "a few days of 'who's this?' head-scratching. The first impression people get until she steps on the convention stage will be through the media."

Callie Crossley, a commentator who works for Harvard's Nieman Foundation, said the initial portrait will be crucial. "If it's positive coverage -- she's a mom, she's caring for a disabled child, she can meet men on their own terms -- if that's the rap that comes through, they are home free," she said of the McCain campaign. "If the coverage is negative, it will be very hard to change the narrative."

Crossley added that Palin may get kicked around by some media types, much as she contends Hillary Clinton was during the primaries. "The sexism in the coverage of these women is usually rampant," she said.

But Tobe Berkovitz, associate dean of Boston University's communications school, said "political correctness" will make it harder for journalists "to put the brass knuckles on a woman after what Hillary went through."

The McCain campaign seemed determined to throw reporters off the scent. Aides did nothing to discourage speculation about Pawlenty, the Minnesota governor, and Romney, the former Massachusetts governor. McCain himself talked up Tom Ridge, the former Pennsylvania governor. And in recent days, the campaign did nothing to tamp down reports by sources close to McCain that he was seriously considering Democrat-turned-Independent Sen. Joe Lieberman.

Though Palin's name was occasionally mentioned on lists of possible McCain choices, no New York Times, Washington Post or Los Angeles Times story in the past month mentioned her as a potential contender. In his New York Times column, Bill Kristol, who is friendly with McCain, wrote last week: "It's awfully tempting for the McCain camp to revisit the possibility of tapping Meg Whitman, the former eBay CEO, Secretary of State Condoleezza Rice, or Gov. Sarah Palin of Alaska. But the first two have never run for office, and Palin has been governor for less than two years."